<!doctype html>
<!--
Copyright 2020 The Immersive Web Community Group

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-->
<html>

<head>
  <meta charset='utf-8'>
  <meta name='viewport' content='width=device-width, initial-scale=1, user-scalable=no'>
  <meta name='mobile-web-app-capable' content='yes'>
  <meta name='apple-mobile-web-app-capable' content='yes'>
  <link rel='icon' type='image/png' sizes='32x32' href='../favicon-32x32.png'>
  <link rel='icon' type='image/png' sizes='96x96' href='../favicon-96x96.png'>
  <link rel='stylesheet' href='../css/common.css'>

  <title>Layer Hit Test</title>
  <!-- Stereo layer dependency -->
  <script src="../js/wglu/wglu-program.js"></script>
  <script src="../js/wglu/wglu-url.js"></script>
  <script src="../js/stereo-util.js"></script>
</head>

<body>
  <header style="max-width: 800px;">
    <details open>
      <summary>Layer Hit Test</summary>
      <p>
        Content rendered using quad/cylinder/equirect/cube layers cannot
        be hit tested directly as these layers do not exist in the projection
        layer. This sample demonstrates a work-around to implement hit test
        on layers by placing transparent placeholders for each quad layer
        in the projection layer.

        Try using the trigger on either controller to select one quad layer,
        and an arrow will indicate the selection.
        <a class="back" href="./index.html">Back</a>
      </p>
    </details>
  </header>
  <main style='text-align: center;'>
    <p>Click 'Enter VR' to see content</p>
  </main>
  <script type="module">
    import { WebXRButton } from '../js/util/webxr-button.js';
    import { Scene, WebXRView } from '../js/render/scenes/scene.js';
    import { Renderer, createWebGLContext } from '../js/render/core/renderer.js';
    import { QueryArgs } from '../js/util/query-args.js';
    import { loadTexture } from '../js/util/texture-loader.js';
    import { QuadNode } from '../js/render/nodes/quad-texture.js';

    const QUAD_TEXTURE_MONO_PATH = '../media/textures/eilenriede-park-2k.png';
    const QUAD_TRANSPARENT_MONO_PATH = '../media/textures/transparent.png';
    const QUAD_ARROW_MONO_PATH = '../media/textures/arrow-up.png';

    // If requested, use the polyfill to provide support for mobile devices
    // and devices which only support WebVR.
    import WebXRPolyfill from '../js/third-party/webxr-polyfill/build/webxr-polyfill.module.js';
    if (QueryArgs.getBool('usePolyfill', true)) {
      let polyfill = new WebXRPolyfill();
    }

    // XR globals.
    let xrButton = null;
    let xrSession = null;
    let xrRefSpace = null;
    let xrGLFactory = null;
    let xrFramebuffer = null;
    let stereoUtil = null;

    // WebGL scene globals.
    let gl = null;
    let renderer = null;
    let scene = new Scene();

    // Layer globals
    let projLayer = null;
    let quadLayer1 = null;
    let quadTexture1 = null;
    let quadTexture1Width = 0;
    let quadTexture1Height = 0;
    let quad1Collider = null;
    let quadLayer2 = null;
    let quadTexture2 = null;
    let quadTexture2Width = 0;
    let quadTexture2Height = 0;
    let quad2Collider = null;

    let selectionArrow = new QuadNode(QUAD_ARROW_MONO_PATH, 0.2, true);
    selectionArrow.translation = [100, 0, 0];
    scene.addNode(selectionArrow);

    function initXR() {
      xrButton = new WebXRButton({
        onRequestSession: onRequestSession,
        onEndSession: onEndSession
      });
      document.querySelector('header').appendChild(xrButton.domElement);

      if (navigator.xr) {
        navigator.xr.isSessionSupported('immersive-vr').then((supported) => {
          xrButton.enabled = supported;
        });
      }
    }

    function onRequestSession() {
      if (!xrSession) {
        navigator.xr.requestSession('immersive-vr', {
          requiredFeatures: ['layers'],
        }).then(onSessionStarted);
      } else {
        onEndSession();
      }
    }

    function initGL() {
      if (gl) { return; }
      gl = createWebGLContext({ xrCompatible: true, webgl2: true, });
      document.body.appendChild(gl.canvas);

      function onResize() {
        gl.canvas.width = gl.canvas.clientWidth * window.devicePixelRatio;
        gl.canvas.height = gl.canvas.clientHeight * window.devicePixelRatio;
      }
      window.addEventListener('resize', onResize);
      onResize();

      renderer = new Renderer(gl);
      scene.setRenderer(renderer);

      // Util for rendering stereo layers
      stereoUtil = new VRStereoUtil(gl);
    }

    function onSessionStarted(session) {
      xrSession = session;
      scene.inputRenderer.useProfileControllerMeshes(session);
      session.addEventListener('end', onSessionEnded);

      initGL();

      xrFramebuffer = gl.createFramebuffer();
      xrGLFactory = new XRWebGLBinding(session, gl);

      session.requestReferenceSpace('local').then((refSpace) => {
        xrRefSpace = refSpace;
        projLayer = xrGLFactory.createProjectionLayer({ space: refSpace, stencil: false });
        session.updateRenderState({ layers: [projLayer] });

        // Loading texture is async, create layer and update render state when done
        quadTexture1 = loadTexture(gl, QUAD_TEXTURE_MONO_PATH, (w, h) => {
          quadTexture1Width = w;
          quadTexture1Height = h;
          quadLayer1 = xrGLFactory.createQuadLayer({
            space: refSpace,
            viewPixelWidth: quadTexture1Width,
            viewPixelHeight: quadTexture1Height,
            layout: "mono",
          });
          quadLayer1.width = 0.5;
          quadLayer1.height = 0.5;
          let pos = { x: -1, y: 0, z: -2 };
          let orient = { x: 0, y: 0, z: 0, w: 1 };
          quadLayer1.transform = new XRRigidTransform(pos, orient);

          // Make transparent placeholder node of the same size for quad layer
          // The placeholder node is in projection layer and thus can be used
          // for hit test
          quad1Collider = new QuadNode(QUAD_TRANSPARENT_MONO_PATH, 1, true);
          quad1Collider.translation = [-1, 0, -2];
          scene.addNode(quad1Collider);
        });

        quadTexture2 = loadTexture(gl, QUAD_TEXTURE_MONO_PATH, (w, h) => {
          quadTexture2Width = w;
          quadTexture2Height = h;
          quadLayer2 = xrGLFactory.createQuadLayer({
            space: refSpace,
            viewPixelWidth: quadTexture2Width,
            viewPixelHeight: quadTexture2Height,
            layout: "mono",
          });
          quadLayer2.width = 0.5;
          quadLayer2.height = 0.5;
          let pos = { x: 1, y: 0, z: -2 };
          let orient = { x: 0, y: 0, z: 0, w: 1 };
          quadLayer2.transform = new XRRigidTransform(pos, orient);

          // Make transparent placeholder node of the same size for quad layer
          // The placeholder node is in projection layer and thus can be used
          // for hit test
          quad2Collider = new QuadNode(QUAD_TRANSPARENT_MONO_PATH, 1, true);
          quad2Collider.translation = [1, 0, -2];
          scene.addNode(quad2Collider);
        });

        session.requestAnimationFrame(onXRFrame);
      });
    }

    function onEndSession() {
      xrSession.end();
    }

    function onSessionEnded(event) {
      if (event.session.isImmersive) {
        xrButton.setSession(null);
      }
      xrSession = null;
      gl = null;
    }

    function onXRFrame(time, frame) {
      let pose = frame.getViewerPose(xrRefSpace);
      xrSession.requestAnimationFrame(onXRFrame);

      if (quadLayer1 && quadLayer2) {
        xrSession.updateRenderState({ layers: [quadLayer1, quadLayer2, projLayer] });
        if (quadLayer1.needsRedraw) {
          let fb = gl.createFramebuffer();
          let glayer = xrGLFactory.getSubImage(quadLayer1, frame);
          gl.bindFramebuffer(gl.FRAMEBUFFER, fb);
          gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, glayer.colorTexture, 0);

          if (quadTexture1Width != 0 && quadTexture1Height != 0) {
            stereoUtil.blit(false, quadTexture1, 0, 0, 1, 1, quadTexture1Width, quadTexture1Height);
          }
        }

        if (quadLayer2.needsRedraw) {
          let fb = gl.createFramebuffer();
          let glayer = xrGLFactory.getSubImage(quadLayer2, frame);
          gl.bindFramebuffer(gl.FRAMEBUFFER, fb);
          gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, glayer.colorTexture, 0);

          if (quadTexture2Width != 0 && quadTexture2Height != 0) {
            stereoUtil.blit(false, quadTexture2, 0, 0, 1, 1, quadTexture2Width, quadTexture2Height);
          }
        }
      }

      if (pose) {
        gl.bindFramebuffer(gl.FRAMEBUFFER, xrFramebuffer);
        scene.updateInputSources(frame, xrRefSpace);

        for (let source of frame.session.inputSources) {
          let gamepad = source.gamepad;
          if (gamepad) {
            if (gamepad.buttons[0].pressed) {
              let targetRayPose = frame.getPose(source.targetRaySpace, xrRefSpace);
              if (!targetRayPose) {
                continue;
              }
              let hitResult = scene.hitTest(targetRayPose.transform);
              if (!hitResult) { continue; }
              if (hitResult.node == quad1Collider) {
                selectionArrow.translation = [-1, -1, -2];
              } else if (hitResult.node == quad2Collider) {
                selectionArrow.translation = [1, -1, -2];
              }
            }
          }
        }

        let views = [];
        for (let view of pose.views) {
          let viewport = null;
          let glLayer = xrGLFactory.getViewSubImage(projLayer, view);
          glLayer.framebuffer = xrFramebuffer;
          viewport = glLayer.viewport;
          gl.bindFramebuffer(gl.FRAMEBUFFER, xrFramebuffer);
          gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, glLayer.colorTexture, 0);
          gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.TEXTURE_2D, glLayer.depthStencilTexture, 0);
          views.push(new WebXRView(view, glLayer, viewport));
        }
        scene.drawViewArray(views);
      }
      scene.endFrame();
    }

    initXR();
  </script>
</body>

</html>